We are attempting to learn if Okazaki pieces in bacteriophage T4 initiate and terminate at unique sites on the chromosome. We obtain Okazaki pieces from T4 infected E. coli cells each of which carries a temperature-sensitive ligase mutation. The pieces are used to transform E. coli cells infected with a series of T4 helper phage. The different helper phage each carry double point mutations within the rII gene: helper phage A - 1,2; helper phage B - 2,3; and helper phage C - 3,4. If Okazaki pieces terminate within a region flanked by two rII markers, then the cotransformation frequency of those markers should be diminished relative to the other pairs of markers, since such cotransformation would require two Okazaki pieces rather than a single piece as for the other pairs of markers. Thus, this transformation system can be used to ask if such termination sites exist, and if so, where they are located. BIBLIOGRAPHIC REFERENCE: Chen, Patricia L. and Philip L. Carl. Genetic Map Location of the Escherichia coli dnaG gene. J. Bact. 124,1613 (1975).